Production of plastic composition materials



Patented Nov. 27, 19281.

UNITED STATES PATENT OFFICE.

CLARENCE A. NASH, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO THE CUTLER-HAM- MEIR MFG. CO., OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

PRODUCTION OF' PLASTIC COMPOSITION MATERIALS.

' No Drawing.

This invention relates to the production of plastic composition materials comprising or containing a binder and a relatively inert filler.

In the production of such materials it has heretofore been customary to effect an initial 1 or incomplete reaction, in one or more stages,

. reaction in the presence total between a phenolic body and an active methylene substance under conditions such that substantially half of such phenolic body is chemically combined with methylene substance and to effect impregnation of the filler with the incomplete condensation product so formed, the material being thereafter molded and subjected to thorough heat treat ment, either subsequent to or during the molding operation, for converting the material of the molded article to a hard and substantially infusible and insoluble state.

While the method just outlined is the outgrowth of protracted development and experimentation and results moreover in an exceedingly valuable product, certain difiiculties thereof as well as certain deficiencies of the product are recognized.

Thus difliculty {has heretofore been ex: perienced in producing uniformly an initial condensation product in the necessary ordesired state of partial reaction, action tends, when once initiated, to progress with extreme rapidity such as to render control and arrest thereof at such desired stage the purpose of obviating such difliculty. Thus it has been proposed to .eflect initial of only a reduced quantity of certain of the agents thereof, whereby the reaction must automatically terminate at or near the desired point. Also in certain cases it has been proposed to effect repeated additions of quantities less than the required quantity of certain agents, permitting each portion to react fully before addition of the ne'xt.. It has also been proosed to introduce various inert solvents for facilitating control and arrest of the reaction. Thus it has been proposed to utilizeas the methylene body -a water solution of formaldehyde, the water thenac'ting as a'reactiong retarding and controlling agent.

it was found desir- However, in such cases to stimulate the reable or even necessary phenolic condensation product since such re- Application filed March 12, 1921. Serial in 451,806.

action by'a suitable condensing or :catalytic agent and when such agent was employed in sufliclent quantities to start the reaction the latter tended to progress with undue rapidity. Also the'use of different oils, and similar solvents for retarding and controlling the reaction has been proposed.

,A further and perhaps more serious difficulty of the aforementioned method relates to the character of the product formed thereby, which product has in the past proven not entirely satisfactory in certain physical respects, the cause of many of such deficiencies having been quite definitely ascertained as thatof inadequate or incomplete impregnation of'the filler material with the binder. Thus Where a fibrous filler is employed under 'the conditions aforestated the binder does notcompletely penetrate and saturate the individual fibres of the filler material but -merely adheres as an exterior coating to aforedescribed process and in the products thereof. I

Another object is that of providing an improved process of the character stated onabling ready and accurate control of the progress of all stages of the reaction between the aforementioned agents, thereby permitting arrest of such reaction with accuracy and iven or desired stage;

precision at any g Another object is that of providing such a method enabling the rate of progress of the reaction to be varied at will within relatively wide limits whereby such accelerated or may be retardedto practically any extent desired. Another objectis that of efiecting a more thorough and complete impregnation of the filler with the binder material 'to thereby effect a greater degree of homogeneity and improved physical properties of the product. Another object is that of providing such a methodenabling and facilitating formation of products corresponding with practically reaction may be after appear.

any desired stage of the reaction between the aforementioned agents as a result of a single continuous reaction, or optionally by the same reaction performed in any desired numberof ste s.

Other objects andadvantages will herein- According to the present invention it is proposed to utilize the filler material itself for rendering the progress of the aforementionedreaction amenable to control and to.

regulate the temperature of the agents undergoing reactionwithin certain fairly definite limits for effecting such control;

It has been found in practice both experimentally and commercially that the filler material, in proportions in which the same may satisfactorily be employed in the finished product, may be utilized-as a highly efiicient,

agent for retardation of the progress of the reaction and that by maintaining suitable temperature control of the agents undergoing such reaction in the presence of the filler the rate of thereaction may be controlled practically as desired.

Without limitation to any particular theory in accounting for the marked retarding efiect of the filler material it is applicants belief, which belief appears to be substantiated in practice, that the fillers ordinarily employed act as heat absorbing bodies whereby the heat liberated as a result of the reaction is dispersed or dissipated and hence the temperature ofthe agents tends to-rise much less rapidly. Otherwise stated, the filler material may be regarded as having a diluting effect upon the various agents, whereby the molecules or molecular groups thereof are more or less separated and hence are less able to combine rapidly with one another.

Whether the effect be due to either of the aforementioned causes or tothe same working in conjunction with one another'or with other causes, it is known that ifthe heat employed to start and promote the reaction be maintained below a fairly definite limit, which limit will ordinarily vary with the character of the filler material and of the active agents employed and with the proportion which the quantity of such filler material bears to the quantity of such active agents, the rate of reaction may be maintained such that the reaction is self-arresting upon discontinuing exceed 17 5 F. If the uantity .of the filler,

be relatively decreased t e reaction tends to progress more rapidly at such temperature whereby such reaction may be more readily controlled if a lower temperature be maintained. However, constant stirring or other agitation of theagents tends to permit control at higher temperatures, whereby under suitable conditions the reaction may be adequately controlled although the temperature rise as high as 220 F., or even higher, whereas obviously at such temperature the total time required to carry the reaction either to completion or to any given or desired intermediate stage is correspondingly reduced.

Thus under the aforementioned conditions of adequate temperature control it is entirely feasible where the desired product corresponds with an incomplete reaction between the agents, by discontinuing or materially reducing the heat supply, to so far retard the progress of the reaction as to permit subjection of samples of the product to the subsequent treatment which is desired or contemplated and to thereby determine thevfitness of the product for such treatment.

By the foregoing steps it is thus possible to effect direct formation of compounds contain-- ing all ingredients which are necessary or desirable in the finished product and at the exact stage of reaction at which the physical properties of the compound are best adapted to the particular kind of subsequent treatment contemplated, the entire reaction being controllable with complete facility for arrest thereof with precision at the desired stage, whereas prior to development of the instant method extreme difficulty has been experienced in effecting arrest of the reaction at an interme-' diate stage even approximating a given or desired stage thereof.

Also, if desired, the reaction when arrested at a relatively early stage may be restarted at any .time and again controlled as formerly for bringing the compound to the desired stage of reaction. In the interval between such successive treatments, the material may be stored, transported or otherwise disposed of without detriment thereto.

Further, it is possible to prepare an initial 7 to contain the phenolic body and methylene substance in practically any desired propor tion but preferably containing sufficient uncombined phenolic body to combine with con-- siderably more than half of the methylene body required in the completed product and to incorporate the filler in such binder. The compound so formed may be thereafter subjected to action of a controlled supply of heat to restart the reaction either subsequent to or during thorough mixing of the binder and filler, the latter then acting as before to retard the reaction and facilitate arrest thereof at the desired stage.

Such incorporation of the filler in the binder prior to reaction of the constituents of the latter, or at a relatively early stage of such reaction, the binder being then in a relatively softer and more fluid state than at later stages of the reaction, facilitates and promotes a much more thorough and complete impregnation of the individual portions, particles or fibres of the filler with binder substance than can be abtained after such later stages of the reaction have been reached. Such more thorough impregnation of the filler with the binder in turn serves to effect very marked improvements in physical prop erties of the finished product. particularly where the subsequent treatment involves forming or molding steps, which steps more 7 over are facilitated by the resultant increased homogeneity of the compound.

As exemplary of the foregoing method, the following preferred procedure may be described: 50 pounds of asbestos is placed in a kneading machine or other suitable form .mixer, together with 16.75 pounds of cresol in which 3.8 pounds of hexamethyleneteramine has been dissolved. Such ingredients I are mixed with one another for from twenty to thirty minutes, or until a homgeneous mass is effected, whereof the asbestos filler is thoroughly impregnated with the cresolof the binder. Subsequently to such mixing operation the compound is placed in a drier and subjected to a moderate degree of heat for initiating chemical reaction between the cresol and hexamethylenetetramine, the mass undergoing reaction being stirred, rotated or otherwise agitated to prevent unequal or lo-' cal heating, and the supply of heat being so controlled that the temperature of the mass does not materially exceed 175 F. The heating is continued until the desired incom lete stage of the reaction is reached, the supp y of heat being then discontinued whereupon the reaction ceases.

The compound containing all the essential ingredients of the finished article is thus brought-by a single simple and readily controlled reaction to a chemical condition suitable for molding or othersubsequent treatment; However, prior to such treatment the material is ordinarily subjected to certain known treatments which may include coolthe ammonia so escaping.

ing,disintegrating, screening and others.

In commercial practice it is desirable to carry out the foregoing treatment of the material in a closed vessel with constant agitation to prevent local heating, suitable means being provided for permitting escape of the liberated ammonia when the internal pressure reaches a. given value, and for collecting Good results are a also attainable bytreating in a closed oven without special provision for keeping constant the relative amounts of the agents.

It is also pos ible to effect the reaction without agitation f the material if the same be treated while spread in the form of thin layers orsheets and preferably subjected on all sides to like temperature conditions.

If the product of the foregoing step is intended for subjection to a quick molding operation at ordinary temperatures the foregoing reaction is preferably arrested at a stage such that substantially half the cresol remains chemically uncombined with hexamethylenetetramine whereas if hot molding of the product is contemplated the reaction may be permitted to progress considerably farther.

To facilitate arrest of the reaction the supply of heat should be so re ulated-that the temperature of the. compound undergoing reaction does not materially exceed 175 degrees F., and under such conditions of heat control, the reaction isv self arresting upon simple discontinuance. of the heat supply. By regulating the temperature between the aforementioned upper limit an'da lower limit corresponding with the lowest temperature at which chemical combination of the aforemen- 'tioned substances is sustained, the rate of reaction may be so controlled that the time required to convert/the uncombined agents to astate suitable for cold molding may be varied from approximately eight hours to fifteen hours or even longer, and at any time during such period the reaction may be terminated by simply cutting off the heat.

For producinga hot molding compound the heat treatment may be continued for a much longer period as from seventy-five to.

one hundred hours, they time being in either case somewhat dependent upon the character of the filler employed and upon the nature time and a sample -of the product submitted to molding or other subse uent treatment under conditions similar to t ose contemplat-- ed, in order to ascertain the fitness of the product for such'subse uent treatment.

If the product of suc reaction is not ine;

tended forimmediate subjection, to the suc ceeding steps of molding and the like it i preferable to discontinue the reaction at a1" relatively early stage as when substantially two-thirds of the cresol remains chemically uncombined with methylene. The product in this condition may be stored for an indefinite I period of time without deterioration or may be transported or otherwise handled, a brief additional heat treatment under the conditions described being thereafter sufficient to render the product suitable for the molding or other subsequent treatment desired.

As a substitute for the foregoing steps, or certain thereof, it is possible and in certain instances desirable to mix the filler with a partially reacted condensation product, for example, one in which approximately butfonethird of the total quantity of cresolrequired is combined with methylene substance, the aforementioned agents being present in substantially the proportions in which the same are adapted to effect complete combination with one another, and .to subjectthe mix to a heat treatment similar to that described for bringing the compound to the desired state of reaction. Also it is possible to employ a phenolic condensation product wherein sub stantially half the phenolic body is .combined with methylene and to incorporate therewith, prior to or concurrently with the addition of the filler, a quantity of unreacted cresol or the like sufficient to provide the desired softness and fluidity of the binder, a corresponding amount of methylene substance being also incorporated, either at the same time or subsequentl to maintain a suitable proportionality o the agents.

A typical mix suitable for performance of the latter-mentioned steps may be composed as follows :-11 pounds of phenolic condensation resin lcomprising' about 10 phenolic groups to six methylene groups; cresol 6 pounds; hexamethylenetetramine (dissolved in the cresol) 2.4 pounds; asbestos pounds.

In each of the foregoing examples the mixing operation may be promoted and a more thorough impregnation of the filler secured if the latter, prior to mixing with the binder, be moistened with a small quantity of a suitable solvent. Thus from one-half to one pint of-coal tar oil ma be preliminarily added to and mixed with t e aforementioned quantity of the asbestos filler. Optionally such solvent may be added to the binder ingredients rather than to the filler, or small quantities of parbinder or mixed with the filler.

aifin, fats, waxes or gums, up to one percent by weight of the binder may be added to the v In each of the aforedescribed methods it is to be understood that substances other than those specifically mentioned maybe substiplaced by phenol or a homologue thereof,

tuted therefor. Thus the. cresol may be red whereas the hexamethylenetetramine or formaldehyde may besimilarly replaced by a polymer thereof or by any other active methylenesubstance suitable for the purpose.

' purposes.

What I claim as new and desire to secure by Letters Patent is:

1. 'A process of producing plastic composition material having as constituents a condensation product binder produced from a phenolic body and an active methylene containing substance, and a relativel inert filler,

which comprises the step of effecting reaction of the complete ingredients of the binder after mixture thereof with the tiller and prior to molding of the mixture, such filler being added in such quantities as to enable arrest of such reaction at a given stage thereof.

2. A process of producing plastic composi- 7 .filler which is relatively inert chemically under the conditions imposed and a binder including products of an incomplete chemical reaction of a phenolic body and an active methylene containing substance which reaction tends to progress at an abnormal rate, which comprises effecting reaction of the complete ingredients of the binder in the. presence of suflicient filler material to facilitatecontrol of progress of the reaction by temperature control of the reaction mixture, such reaction being effected prior to molding of the material.

4. The process of producing plastic composition material having as constituents a relatively inert filler and a binder including a phenolic body and an active methylene containing substance, which ingredients are potentially reactive for producing a'substantially anhydrous condensation product, which comprises effecting chemical reaction involving the complete constituents of the binder in'the presence of a sufiicient quantity of the filler to fa'oilitate control of reaction progress through controlling the temperature of the reacting agents, such reaction being effected prior to molding of the mate rials. v

v 5. The process of producing plastic composition material including as constituents a relatively inert' filler and a binder having constituents, comprising a phenolic body and an active I methylene containing substance, which'are otentially reactive to produce a substantial y anhydrouscondensation product, which comprises mixin a quantity of the filler with a body including potentially lOO tion and discontinuing the suppl to a temperature above heating the mixture such binder conthe reaction temperature of stituents for promoting reaction thereof an adjusting such quantity of the filler to facilitate arrest of the reaction through-controlling the temperature of such constituents, such reaction being effected prior to molding of the material.

6. The process of producing plastic composition material including as constituents a relatively inert filler and a binder having ingredients, comp-rising a phenolic body and an active methylene containing substance, which are potentially reactive for producing a substantially anhydrous condensation product, which comprises mixing with a body including potentially reactive complete ingredients of the binder a quantity of the filler material sufficient to render the reaction amenable to temperature control, heating the mixture to a temperature above the reaction temperature but below the temperature at which the reaction is self maintaining under such condition, utilizing such filler material to controlthe progress of the resultant reacof heat for arrest of the reaction as desirec such reaction being effected prior to molding of the material.

7. The process of roducing plastic composition material, wliich comprises mixing together a substantially-inert filler and binder in redients comprising phenolic and ene substances in substantially the proportions in which said substances are adapted to effect complete chemical combination with one another by a reaction which tends to resist arrest thereof, at least considerably more than half the total quantity of such substances present being in a potentially reactive state and the filler being present in sufficient quantitiesi'to render the reaction amenable to temperature control,

methy heat treating the mixture below the temperature at which the resultant reaction becomes automatic and utilizing the filler in controlling arrest of such reaction as desired,

such reaction being efiected prior to molding of the material. i

8. The process of producing plastic com position material whichcomprises mixing together a substantially inert filler and binder comprising phenolic and substantially anhy drous methylene substances in proportions providing for substantially complete chemiat least considerably cal combination thereof,

- more than fifty percent, of the total quantity of such substances present being in a potentially reactive state, and the filler being pres ent in s-uflicient quantities to render thereaction amenable to temperature control, heat treating the mixture b low the temperature at which the resultant reaction becomes automatic, utilizing the filler in controlling such reaction and discontinuing such heat treatment for arrest of the reaction.

.capable of efiepting chemical combination with one another, incorporating in such mixture a relatively inert filler, subjecting the compound to prolonged heat treatment at moderate temperature above that at which the potentially combine, discontinuing the heat treatment for arrest of the resultant reaction at a stage such that substantially half the total number of the respective groups present are chemically combined with one another and thereafter subjecting the product to a further heat treatment for carrylng forward the reaction.

10. The process which comprises mixing together cresol and hexamethylenetetramine in proportions affording approximately six molecules of the former to one molecule of the latter, incorporating in the mixture a quantity of a substantially inert filler material, heat treating the resultant compound for several hours at a. temperature of approximately 17 5 degrees F., interrupting the supply of heat for arrest of the resultant reaction at a stage wherein approximately halfithe phenolic groups present are chemically combined with methylene groups and renewing the heat treatment for advancing the reaction to a stage wherein the product is in a condition suitable for subsequent treatment.

11. The process of producing articles comprising or containing a substantially anhy drous condensation product binder of a phenolic body and an active methylene containing substance, and a relatively inert filler, which comprises effecting a reaction involving chemically active complete constituents of the product after addition ofsufiicient filler material thereto to enable control and arrest of the reaction through temperature control of the reaction mixture, arresting the reaction at a given incomplete stage thereof through such temperature control prior to molding, and then subjecting the resultant compound to subsequent treatment including thorough heat treatment for curing.

12. The process of producing articles comprising or containing a substantially anhydrous condensation product of a phenohc body and an active methylene containing substance, and a rel, tively inert filler, which comthereto to enable control and arrest of the reaction through temperature control of the ses mixing tod gether phenolic condensation product con}; 7

reactive agents are adapted to reaction mixture, arresting the reaction at a given incomplete stage through such temperachemically active complete constituents of the product after addition of suiiicient filler material thereto to retard progress of such reaction, effecting temper rture control for arresting the reaction at a given incomplete stage thereof prior to molding of the compound and subjecting the resultant compound to subsequent treatment including molding under pressure and heat treatment to complete the reaction.

14. The process of producing plastic composition material adapted to form giving treatment and heat hardening, which comprises efli'ecting partial condensation reaction between the required total quantities of substances capable of furnishing approximately equal numbers of phenolic and'methylene groups respectively, such partial condensation reaction being efiected prior to molding of the material andbeing maintained amenable to control by incorporating with the potentially reactive substances aquantity ofnonreactivematerial suflicient too-retard said reaction, said non reactive material being adapted to remain in situ as a constituent of the product.

15. In a process of producing plastic material by an incomplete. condensation reaction of a phenolic body and an active methylene containing substance, which reaction tends to approach completion prematurely, the step whlch comprises retarding such reaction by causing at least certain stages thereof to be enacted prior to molding in the presence of a reaction retarding quantity of a material adapted to remain in situ as a constituent of the product.

16. In a, process of producing plastic mater-lal comprising a relatively inert fillrl and a binder which is the product of incomplete condensation of the total nolic and methylene substances employed by a reaction which tends to approachcomplequantities of phe- I a binder which is the product of incomplete condensation of phenolic and methylene substances by a reaction which tends to approach completion prematurely, which comprises incorporation of the filler with the complete ingredients of the binderrat a stage such as to provide for retardation of the later stages of the incomplete condensation reaction prior to molding, as a result of the presence of the filler, and supplementary temperature control of the reacting ingredients for control and arrest of the reaction to render said material adaptable for molding under pressure.

18. A composition material comprlsing a relatively inert filler and a binder having approximately equal numbers of phenolic and methylene groups, at least substantially more than half of the phenolic groups bein un-- combined with methylene groups and sing free, and which except for the presence of said filler would unite with one another by a reaction which when initiated tends to proceed to completion prematurely.

19. A plastic composition material suitable for molding, which comprises a phenolic body and an active methylene containing substance reacted prior to molding of the material in the presence of a quantity of filler suflicient to render such reaction amenable to quantitative control through heat regulation.

20. A plastic composition material suitable for molding, which comprises complete condensation product constituents including i a phenolic body and an active methylene containing substance reacted together in the presence of a quantity of filler to a stage whereinsubstantially one-half of the phe nolic groups present are in a potentially reactive state, the quantity of filler employed being so proportioned with reference to the quantity. of condensation product constitucuts, as to render the reaction amenable to control and arrest at the stage aforeindicated through temperature regulation.

In Witness whereof, I have hereunto subscribed my name.

CLARENCE A. NASH. 

